/*
 * libcxgb_ppm.c: Chelsio common library for T3/T4/T5 iSCSI PagePod Manager
 *
 * Copyright (c) 2016 Chelsio Communications, Inc. All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *      - Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer.
 *
 *      - Redistributions in binary form must reproduce the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer in the documentation and/or other materials
 *        provided with the distribution.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 *
 * Written by: Karen Xie (kxie@chelsio.com)
 */

#define DRV_NAME "libcxgb"
#define DRV_VERSION "1.0.0-ko"
#define pr_fmt(fmt) DRV_NAME ": " fmt

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/debugfs.h>
#include <linux/export.h>
#include <linux/list.h>
#include <linux/skbuff.h>
#include <linux/pci.h>
#include <linux/scatterlist.h>

#include "libcxgb_ppm.h"

/* Direct Data Placement -
 * Directly place the iSCSI Data-In or Data-Out PDU's payload into
 * pre-posted final destination host-memory buffers based on the
 * Initiator Task Tag (ITT) in Data-In or Target Task Tag (TTT)
 * in Data-Out PDUs. The host memory address is programmed into
 * h/w in the format of pagepod entries. The location of the
 * pagepod entry is encoded into ddp tag which is used as the base
 * for ITT/TTT.
 */

/* Direct-Data Placement page size adjustment
 */
int cxgbi_ppm_find_page_index(struct cxgbi_ppm *ppm, unsigned long pgsz)
{
        struct cxgbi_tag_format *tformat = &ppm->tformat;
        int i;

        for (i = 0; i < DDP_PGIDX_MAX; i++) {
                if (pgsz == 1UL << (DDP_PGSZ_BASE_SHIFT +
                                         tformat->pgsz_order[i])) {
                        pr_debug("%s: %s ppm, pgsz %lu -> idx %d.\n",
                                 __func__, ppm->ndev->name, pgsz, i);
                        return i;
                }
        }
        pr_info("ippm: ddp page size %lu not supported.\n", pgsz);
        return DDP_PGIDX_MAX;
}

/* DDP setup & teardown
 */
static int ppm_find_unused_entries(unsigned long *bmap,
                                   unsigned int max_ppods,
                                   unsigned int start,
                                   unsigned int nr,
                                   unsigned int align_mask)
{
        unsigned long i;

        i = bitmap_find_next_zero_area(bmap, max_ppods, start, nr, align_mask);

        if (unlikely(i >= max_ppods) && (start > nr))
                i = bitmap_find_next_zero_area(bmap, max_ppods, 0, start - 1,
                                               align_mask);
        if (unlikely(i >= max_ppods))
                return -ENOSPC;

        bitmap_set(bmap, i, nr);
        return (int)i;
}

static void ppm_mark_entries(struct cxgbi_ppm *ppm, int i, int count,
                             unsigned long caller_data)
{
        struct cxgbi_ppod_data *pdata = ppm->ppod_data + i;

        pdata->caller_data = caller_data;
        pdata->npods = count;

        if (pdata->color == ((1 << PPOD_IDX_SHIFT) - 1))
                pdata->color = 0;
        else
                pdata->color++;
}

static int ppm_get_cpu_entries(struct cxgbi_ppm *ppm, unsigned int count,
                               unsigned long caller_data)
{
        struct cxgbi_ppm_pool *pool;
        unsigned int cpu;
        int i;

        cpu = get_cpu();
        pool = per_cpu_ptr(ppm->pool, cpu);
        spin_lock_bh(&pool->lock);
        put_cpu();

        i = ppm_find_unused_entries(pool->bmap, ppm->pool_index_max,
                                    pool->next, count, 0);
        if (i < 0) {
                pool->next = 0;
                spin_unlock_bh(&pool->lock);
                return -ENOSPC;
        }

        pool->next = i + count;
        if (pool->next >= ppm->pool_index_max)
                pool->next = 0;

        spin_unlock_bh(&pool->lock);

        pr_debug("%s: cpu %u, idx %d + %d (%d), next %u.\n",
                 __func__, cpu, i, count, i + cpu * ppm->pool_index_max,
                pool->next);

        i += cpu * ppm->pool_index_max;
        ppm_mark_entries(ppm, i, count, caller_data);

        return i;
}

static int ppm_get_entries(struct cxgbi_ppm *ppm, unsigned int count,
                           unsigned long caller_data)
{
        int i;

        spin_lock_bh(&ppm->map_lock);
        i = ppm_find_unused_entries(ppm->ppod_bmap, ppm->bmap_index_max,
                                    ppm->next, count, 0);
        if (i < 0) {
                ppm->next = 0;
                spin_unlock_bh(&ppm->map_lock);
                pr_debug("ippm: NO suitable entries %u available.\n",
                         count);
                return -ENOSPC;
        }

        ppm->next = i + count;
        if (ppm->next >= ppm->bmap_index_max)
                ppm->next = 0;

        spin_unlock_bh(&ppm->map_lock);

        pr_debug("%s: idx %d + %d (%d), next %u, caller_data 0x%lx.\n",
                 __func__, i, count, i + ppm->pool_rsvd, ppm->next,
                 caller_data);

        i += ppm->pool_rsvd;
        ppm_mark_entries(ppm, i, count, caller_data);

        return i;
}

static void ppm_unmark_entries(struct cxgbi_ppm *ppm, int i, int count)
{
        pr_debug("%s: idx %d + %d.\n", __func__, i, count);

        if (i < ppm->pool_rsvd) {
                unsigned int cpu;
                struct cxgbi_ppm_pool *pool;

                cpu = i / ppm->pool_index_max;
                i %= ppm->pool_index_max;

                pool = per_cpu_ptr(ppm->pool, cpu);
                spin_lock_bh(&pool->lock);
                bitmap_clear(pool->bmap, i, count);

                if (i < pool->next)
                        pool->next = i;
                spin_unlock_bh(&pool->lock);

                pr_debug("%s: cpu %u, idx %d, next %u.\n",
                         __func__, cpu, i, pool->next);
        } else {
                spin_lock_bh(&ppm->map_lock);

                i -= ppm->pool_rsvd;
                bitmap_clear(ppm->ppod_bmap, i, count);

                if (i < ppm->next)
                        ppm->next = i;
                spin_unlock_bh(&ppm->map_lock);

                pr_debug("%s: idx %d, next %u.\n", __func__, i, ppm->next);
        }
}

void cxgbi_ppm_ppod_release(struct cxgbi_ppm *ppm, u32 idx)
{
        struct cxgbi_ppod_data *pdata;

        if (idx >= ppm->ppmax) {
                pr_warn("ippm: idx too big %u > %u.\n", idx, ppm->ppmax);
                return;
        }

        pdata = ppm->ppod_data + idx;
        if (!pdata->npods) {
                pr_warn("ippm: idx %u, npods 0.\n", idx);
                return;
        }

        pr_debug("release idx %u, npods %u.\n", idx, pdata->npods);
        ppm_unmark_entries(ppm, idx, pdata->npods);
}
EXPORT_SYMBOL(cxgbi_ppm_ppod_release);

int cxgbi_ppm_ppods_reserve(struct cxgbi_ppm *ppm, unsigned short nr_pages,
                            u32 per_tag_pg_idx, u32 *ppod_idx,
                            u32 *ddp_tag, unsigned long caller_data)
{
        struct cxgbi_ppod_data *pdata;
        unsigned int npods;
        int idx = -1;
        unsigned int hwidx;
        u32 tag;

        npods = (nr_pages + PPOD_PAGES_MAX - 1) >> PPOD_PAGES_SHIFT;
        if (!npods) {
                pr_warn("%s: pages %u -> npods %u, full.\n",
                        __func__, nr_pages, npods);
                return -EINVAL;
        }

        /* grab from cpu pool first */
        idx = ppm_get_cpu_entries(ppm, npods, caller_data);
        /* try the general pool */
        if (idx < 0)
                idx = ppm_get_entries(ppm, npods, caller_data);
        if (idx < 0) {
                pr_debug("ippm: pages %u, nospc %u, nxt %u, 0x%lx.\n",
                         nr_pages, npods, ppm->next, caller_data);
                return idx;
        }

        pdata = ppm->ppod_data + idx;
        hwidx = ppm->base_idx + idx;

        tag = cxgbi_ppm_make_ddp_tag(hwidx, pdata->color);

        if (per_tag_pg_idx)
                tag |= (per_tag_pg_idx << 30) & 0xC0000000;

        *ppod_idx = idx;
        *ddp_tag = tag;

        pr_debug("ippm: sg %u, tag 0x%x(%u,%u), data 0x%lx.\n",
                 nr_pages, tag, idx, npods, caller_data);

        return npods;
}
EXPORT_SYMBOL(cxgbi_ppm_ppods_reserve);

void cxgbi_ppm_make_ppod_hdr(struct cxgbi_ppm *ppm, u32 tag,
                             unsigned int tid, unsigned int offset,
                             unsigned int length,
                             struct cxgbi_pagepod_hdr *hdr)
{
        /* The ddp tag in pagepod should be with bit 31:30 set to 0.
         * The ddp Tag on the wire should be with non-zero 31:30 to the peer
         */
        tag &= 0x3FFFFFFF;

        hdr->vld_tid = htonl(PPOD_VALID_FLAG | PPOD_TID(tid));

        hdr->rsvd = 0;
        hdr->pgsz_tag_clr = htonl(tag & ppm->tformat.idx_clr_mask);
        hdr->max_offset = htonl(length);
        hdr->page_offset = htonl(offset);

        pr_debug("ippm: tag 0x%x, tid 0x%x, xfer %u, off %u.\n",
                 tag, tid, length, offset);
}
EXPORT_SYMBOL(cxgbi_ppm_make_ppod_hdr);

static void ppm_free(struct cxgbi_ppm *ppm)
{
        vfree(ppm);
}

static void ppm_destroy(struct kref *kref)
{
        struct cxgbi_ppm *ppm = container_of(kref,
                                             struct cxgbi_ppm,
                                             refcnt);
        pr_info("ippm: kref 0, destroy %s ppm 0x%p.\n",
                ppm->ndev->name, ppm);

        *ppm->ppm_pp = NULL;

        free_percpu(ppm->pool);
        ppm_free(ppm);
}

int cxgbi_ppm_release(struct cxgbi_ppm *ppm)
{
        if (ppm) {
                int rv;

                rv = kref_put(&ppm->refcnt, ppm_destroy);
                return rv;
        }
        return 1;
}
EXPORT_SYMBOL(cxgbi_ppm_release);

static struct cxgbi_ppm_pool *ppm_alloc_cpu_pool(unsigned int *total,
                                                 unsigned int *pcpu_ppmax)
{
        struct cxgbi_ppm_pool *pools;
        unsigned int ppmax = (*total) / num_possible_cpus();
        unsigned int max = (PCPU_MIN_UNIT_SIZE - sizeof(*pools)) << 3;
        unsigned int bmap;
        unsigned int alloc_sz;
        unsigned int count = 0;
        unsigned int cpu;

        /* make sure per cpu pool fits into PCPU_MIN_UNIT_SIZE */
        if (ppmax > max)
                ppmax = max;

        /* pool size must be multiple of unsigned long */
        bmap = BITS_TO_LONGS(ppmax);
        ppmax = (bmap * sizeof(unsigned long)) << 3;

        alloc_sz = sizeof(*pools) + sizeof(unsigned long) * bmap;
        pools = __alloc_percpu(alloc_sz, __alignof__(struct cxgbi_ppm_pool));

        if (!pools)
                return NULL;

        for_each_possible_cpu(cpu) {
                struct cxgbi_ppm_pool *ppool = per_cpu_ptr(pools, cpu);

                memset(ppool, 0, alloc_sz);
                spin_lock_init(&ppool->lock);
                count += ppmax;
        }

        *total = count;
        *pcpu_ppmax = ppmax;

        return pools;
}

int cxgbi_ppm_init(void **ppm_pp, struct net_device *ndev,
                   struct pci_dev *pdev, void *lldev,
                   struct cxgbi_tag_format *tformat,
                   unsigned int ppmax,
                   unsigned int llimit,
                   unsigned int start,
                   unsigned int reserve_factor)
{
        struct cxgbi_ppm *ppm = (struct cxgbi_ppm *)(*ppm_pp);
        struct cxgbi_ppm_pool *pool = NULL;
        unsigned int ppmax_pool = 0;
        unsigned int pool_index_max = 0;
        unsigned int alloc_sz;
        unsigned int ppod_bmap_size;

        if (ppm) {
                pr_info("ippm: %s, ppm 0x%p,0x%p already initialized, %u/%u.\n",
                        ndev->name, ppm_pp, ppm, ppm->ppmax, ppmax);
                kref_get(&ppm->refcnt);
                return 1;
        }

        if (reserve_factor) {
                ppmax_pool = ppmax / reserve_factor;
                pool = ppm_alloc_cpu_pool(&ppmax_pool, &pool_index_max);

                pr_debug("%s: ppmax %u, cpu total %u, per cpu %u.\n",
                         ndev->name, ppmax, ppmax_pool, pool_index_max);
        }

        ppod_bmap_size = BITS_TO_LONGS(ppmax - ppmax_pool);
        alloc_sz = sizeof(struct cxgbi_ppm) +
                        ppmax * (sizeof(struct cxgbi_ppod_data)) +
                        ppod_bmap_size * sizeof(unsigned long);

        ppm = vmalloc(alloc_sz);
        if (!ppm)
                goto release_ppm_pool;

        memset(ppm, 0, alloc_sz);

        ppm->ppod_bmap = (unsigned long *)(&ppm->ppod_data[ppmax]);

        if ((ppod_bmap_size >> 3) > (ppmax - ppmax_pool)) {
                unsigned int start = ppmax - ppmax_pool;
                unsigned int end = ppod_bmap_size >> 3;

                bitmap_set(ppm->ppod_bmap, ppmax, end - start);
                pr_info("%s: %u - %u < %u * 8, mask extra bits %u, %u.\n",
                        __func__, ppmax, ppmax_pool, ppod_bmap_size, start,
                        end);
        }

        spin_lock_init(&ppm->map_lock);
        kref_init(&ppm->refcnt);

        memcpy(&ppm->tformat, tformat, sizeof(struct cxgbi_tag_format));

        ppm->ppm_pp = ppm_pp;
        ppm->ndev = ndev;
        ppm->pdev = pdev;
        ppm->lldev = lldev;
        ppm->ppmax = ppmax;
        ppm->next = 0;
        ppm->llimit = llimit;
        ppm->base_idx = start > llimit ?
                        (start - llimit + 1) >> PPOD_SIZE_SHIFT : 0;
        ppm->bmap_index_max = ppmax - ppmax_pool;

        ppm->pool = pool;
        ppm->pool_rsvd = ppmax_pool;
        ppm->pool_index_max = pool_index_max;

        /* check one more time */
        if (*ppm_pp) {
                ppm_free(ppm);
                ppm = (struct cxgbi_ppm *)(*ppm_pp);

                pr_info("ippm: %s, ppm 0x%p,0x%p already initialized, %u/%u.\n",
                        ndev->name, ppm_pp, *ppm_pp, ppm->ppmax, ppmax);

                kref_get(&ppm->refcnt);
                return 1;
        }
        *ppm_pp = ppm;

        ppm->tformat.pgsz_idx_dflt = cxgbi_ppm_find_page_index(ppm, PAGE_SIZE);

        pr_info("ippm %s: ppm 0x%p, 0x%p, base %u/%u, pg %lu,%u, rsvd %u,%u.\n",
                ndev->name, ppm_pp, ppm, ppm->base_idx, ppm->ppmax, PAGE_SIZE,
                ppm->tformat.pgsz_idx_dflt, ppm->pool_rsvd,
                ppm->pool_index_max);

        return 0;

release_ppm_pool:
        free_percpu(pool);
        return -ENOMEM;
}
EXPORT_SYMBOL(cxgbi_ppm_init);

unsigned int cxgbi_tagmask_set(unsigned int ppmax)
{
        unsigned int bits = fls(ppmax);

        if (bits > PPOD_IDX_MAX_SIZE)
                bits = PPOD_IDX_MAX_SIZE;

        pr_info("ippm: ppmax %u/0x%x -> bits %u, tagmask 0x%x.\n",
                ppmax, ppmax, bits, 1 << (bits + PPOD_IDX_SHIFT));

        return 1 << (bits + PPOD_IDX_SHIFT);
}
EXPORT_SYMBOL(cxgbi_tagmask_set);

MODULE_AUTHOR("Chelsio Communications");
MODULE_DESCRIPTION("Chelsio common library");
MODULE_VERSION(DRV_VERSION);
MODULE_LICENSE("Dual BSD/GPL");